(a) Field of the Invention
The present invention relates to bonding apparatus and method of metal plates. More particularly, the present invention relates to bonding apparatus and method of metal plates where a bonding process is simplified and bonding strength is improved.
(b) Description of the Related Art
Generally, two methods for bonding thin metal plates are known. The first method is spot welding, and the second method is rivet bonding. In spot welding, an electrical voltage is applied to overlapped metal plates, and heat is generated therein since the metal plates have electrical resistance. In this case, if a pressure is applied to the overlapped metal plates, overlapped surfaces of the metal plates are melted and the metal plates are bonded.
In rivet bonding, two metal plates are bored and bonded with a rivet.
The two methods each have merits. However, arcing and environmental pollution may occur since a high voltage is applied to the metal plates in spot welding. In addition, the resulting bonded surface may not be even.
Rivet bonding has advantages in that bonding strength is high and the bonding process is performed at room temperature. However, if one rivet is used for bonding metal plates, normal bonding force and shearing bonding force between the metal plates may be strong but the metal plates may rotate with respect to each other. Accordingly, multiple rivets must be used so that the metal plates do not rotate. In addition, manufacture of a rivet head must be done first, and holes of the metal plates must be aligned so that the rivet is inserted therein.
Recently, a self-piercing rivet bonding method has been developed in order to make up for such drawbacks of the rivet bonding method. In the self-piercing rivet bonding method, holes are bored in the metal plates and simultaneously molten pools are formed in the metal plates by frictional heat between the metal plates and the rivet, which bonds the metal plates.
However, in the self-piercing rivet bonding method, manufacture of a self-piercing rivet must be done first, and the self-piercing rivet must be rotated in order to bond the metal plates by the frictional heat.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.